1. Field of the Invention
The present invention relates to a vehicle body and more particularly to a vehicle lower body structure. More specifically, the present invention pertains to a reinforcement structure of a vehicle rear lower body.
2. Description of the Prior Art
Conventional motor vehicle body structures have side sills of a closed cross section extending along the opposite sides of a floor panel. At the rear portion, there is a cross member extending transversely and connected with the floor panel to form a structure of a closed cross section. The cross member is connected at the opposite ends to the respective side sills. In the Japanese utility model application No. 53-180904 filed on Dec. 25, 1978 and published for public inspection on June 30, 1980 under the disclosure No. 55-94280, there is proposed to provide a cross member of an increased heightwise dimension so that it extends upwards at the opposite ends beyond the upper edges of the side sills. The purpose of this cross member structure is to make it possible to block the side door against coming into the passanger compartment in case of a sideward collision of the vehicle.
Conventional rear lower body structures are considered as providing a satisfactory rigidity as long as the vehicle body has a rigid roof structure. It should however be noted that in case of a convertible or open top vehicle, the roof structure does not contribute to the rigidity of the body structure so that the cross member cannot provide a sufficient torsional rigidity. Even in the body structure as proposed by the aforementioned Japanese utility model, the cross does not contribute to the torsional rigidity to a satisfactory level because the cross member is connected at the opposite ends only to the side sills.